1. Field of the Invention
High-pressure oxygen is commonly used in various medical devices and diving equipment as well as a typical oxidizer for liquid bipropellant propulsion systems in manned and unmanned spacecraft.
This invention relates to testing apparatus for evaluating the suitability of materials that are proposed to be used in equipment which will utilize high-pressure gases or will be exposed to high-pressure gaseous environments. More particularly, the present invention is related to a new and improved high-pressure promoted combustion chamber for conducting multiple real-time analyses of metallic and nonmetallic test samples subjected to inert or oxidizing gases under selectively-controlled environmental conditions.
2. Background Art
Heretofore environmental test chambers such as shown in U.S. Pat. Nos. 2,659,235, 2,917,927 and 2,937,530 have been employed for determining if various electrical or mechanical devices can be safely operated in a potentially-explosive gaseous atmosphere without generating excessive heat or creating sparks that might possibly ignite the gaseous mixture. Typically these test chambers include an explosion-resistant enclosure sized to contain the device that is to be tested and a blower for circulating the potentially-explosive gas through the test chamber. The test is then conducted by operating the device inside of the enclosure to determine if an explosion occurs when the device is operated in that particular environment.
To test combustible materials such as synthetic fabrics, a so-called "autoignition" test chamber such as shown in U.S. Pat. No. 3,578,756 is arranged to allow a selected gas to be maintained at a moderate constant pressure inside of the chamber while minute gas samples are periodically withdrawn to determine whether the test specimen is being decomposed. The internal temperature of the chamber is controlled by immersing the chamber in a liquid bath whose temperature is periodically varied during the course of the test. In this way, a series of measurements representative of the decomposition of the tested material are obtained for given temperature ranges and gaseous environments.
In addition to determining whether particular devices can be safely used in potentially-explosive environments, it is particularly useful to establish the flammability or so-called "flame propagation" of various materials that will be subjected to these hazardous environments. A test device which has been found to be well suited for determining the flammability of various plastics and other non-metallic combustible materials in hazardous environments is disclosed in U.S. Pat. No. 3,545,252. As fully described there, a material specimen that is to be tested is put in an enclosed chamber and a source of low-pressure gas is connected to the test chamber. An electric heating coil inside of the test chamber is then selectively positioned in relation to the specimen to control the amount of heat that is being applied to the specimen. A plexiglass window is arranged in one end of the chamber so that laboratory personnel can observe the test specimen as well as accurately position the coil.
Many of the technological advances in aerospace and in medicine in recent years make it essential to evaluate the suitability of materials which are being considered for potential service in gaseous environments. One of the most critical tests of this nature is to determine whether non-combustible materials can be safely used in high-pressure oxygen-enriched environments. Heretofore these evaluation tests have been conducted by enclosing a representative sample of a proposed material in a test chamber and simply subjecting the test sample to a controlled environment for a given length of time to determine whether that material can withstand a particular environmental condition. Although these tests are useful, such static tests are nevertheless limited since only post-test analyses can be made of the remains of the test sample. It is, of course, appreciated by those skilled in the art that with the typical static test chambers of the prior art, investigators are unable to make real-time studies of the flame propagation of materials under predetermined dynamic test conditions in high-pressure inert or oxidizing gaseous environments.